Human intelligence separates our species from
other lifeforms in a countless number of ways. Our ability to use knowledge and reason to plan
for the future has provided us with unparalleled ability to bring our aspirations to reality.
But our intelligence and foresight comes with a dark side: the anxiety-inducing knowledge of
that which has always been out of our control, that none of our planning ability
has ever been able to change; that we will eventually grow old and die.
Humanity has developed numerous psychological approaches to deal with this truth. We repress
it – denying it or avoiding thinking about it, we provide meaning to it through symbolism,
philosophy, and religious belief. But there is another strategy humanity has long dreamed
of that modern science has made possible for the first time: we can work to change what
has always been true through all of life’s history; we can try to engineer our life’s
extension and possibly even our immortality. As far back as 210 BCE, China’s first emperor
Qin Shihuang ordered a nationwide hunt for an elixir of immortality. Jumping forward to
the 3rd century AD and continuing for more than a millenia, alchemists sought to create a
“philosopher’s stone” that could restore youth and grant immortality… and also turn metals into
gold while it's at it. Perhaps most famous is the legend of Spanish explorer Juan Ponce de León’s
1513 expedition searching for the Fountain of Youth, although historians believe this purpose
behind his travels to be a myth. Today, however, we have a much better understanding of
aging to make a more serious attempt. Life span is highly variable between species.
Life history theory posits that species evolve to not live past the point where they stop
contributing to reproductive success. Species with high reproduction rates, such as rodents
or many bacteria, tend to have shorter lives, small bodies, and rapidly mature to reproductive
age. Meanwhile species that have less children but dedicate more effort into ensuring
their success, such as elephants or whales, tend to reach a larger size and live longer.
There are many exceptions to this general trend, however. And there are at least two known life
forms that appear to have evolved the potential for immortality. The Turritopsis dohrnii
jellyfish is less than 1/5th of an inch long, and under certain specific conditions can revert
to a younger form and rejuvenate its cells, and repeat the process indefinitely; individual
jellyfish have been known to live over 500 years. Also of the Cnidaria phylum, Hydra appear to show
no signs of aging, though the oldest identified individual was only 41. Although not capable of
true immortality, glass sponges are believed to be the animal with the greatest practical longevity,
with one individual of the Scolymastra joubini species estimated to be 15,000 years old,
the single oldest living animal on earth. While hardly in league with a glass sponge, humans
have an above average life span. As of 2019, before the COVID pandemic, the United Nations
estimated the average lifespan of humans across the world to be 72.6 years, although highly
variable by nation, with the Central African Republic having the lowest life expectancy at 53
years old and Japan having the longest at 84. And globally, women have a longer life expectancy
than men, due to a combination of biological, behavioral, and environmental factors. But
everywhere and for both sexes average life expectancy has increased enormously over time,
with the global average being only 29 years in 1800, not much improved from the Bronze Age,
when average life expectancy was only 26. Thinking in terms of “average” lifespan is
somewhat misleading, however. Life expectancy at birth has through most of human existence
been dragged down by high rates of infant and child mortality. Those who did make it to
adulthood were very likely to live decades longer. It’s estimated that throughout most of
human history, approximately 27% of infants died before reaching their first birthday, and 46%
died before reaching the age of 15. But over the course of the 20th century those rates rapidly
declined, driven primarily by the increased wealth from the industrial revolution and with it
food availability, sanitation, personal hygiene, antibiotics, vaccination, and developments
in the field of pediatrics. As of 2017, the global infant mortality rate was only
2.9%, and only 4.6% died before age 15. The monumental increase in human wealth over
the 20th century has not merely saved infants, but provided resources to spend on healthcare
and study diseases that affect all ages. The “Preston Curve” demonstrates that as a
nation’s gross domestic product rises, so does its life expectancy, primarily
through improvements in health technology. The longest verified human lifespan – though
still subject to some amount of skepticism by critics – is of Frenchwoman Jeanne Calment,
who died at 122 years and 164 days old in 1997. Scientists using a cutting edge computer
model have estimated that at present, the maximum theoretically possible human lifespan
given our biological limits, even with the best health and genetics, is 150 years old. That
model, however, assumes no development in the medical treatments for aging available to
us. That’s a lot of years you can use to like Beyond Now’s videos and subscribe to our channel,
but we’d love for you to have even more time. The promise and hope for the future is that humanity
can engineer our way out of our own mortality. How might this happen? Well, to solve
that problem, scientists first have to understand what aging even actually is.
Biologists have identified twelve interconnected biochemical hallmarks of aging, all of which
present possible targets to change our fate: “Genome instability,” “telomere shortening,”
“epigenomic alterations,” “loss of proteostasis,” “deregulated nutrient sensing,” “mitochondrial
dysfunction,” “cellular senescence,” “disabled macroautophagy,” “stem cell exhaustion,”
“altered intercellular communication,” “chronic inflammation,” and “dysbiosis.”
Some potential strategies to target these hallmarks of aging are relatively simple and
available to us today. A healthy diet is a simple intervention most already understand can
improve and extend our life, but certain chemicals in foods such as the omega-3 oils common in
fish, spermidine common in fungi and green peas, and various flavonoids which give foods their
color, are all being investigated for their specific ability to promote longevity through
varying mechanisms. Some of these chemicals can be ingested as supplements in doses far beyond those
that would be possible to consume in a normal diet, although it's important to first consult
with one’s doctor on the safety and efficacy of doing so. Recent evidence has also demonstrated
that caloric restriction through intermittent fasting, or simply eating less, may be
surprisingly powerful in optimizing intercellular communication, autophagy, and DNA repair.
Temperature is another factor that appears to have a large effect on aging. One study showed
that reducing the core body temperature of mice by 0.5 degrees celsius extended their lifespan by
20%. Reducing core body temperature is difficult, with that study requiring risky changes to
those mice’s brains, but another simpler strategy showing promise for slowing aging could
be simply lowering your thermostat. An ambient temperature of 18 degrees celsius (64.4 degrees
fahrenheit) has been shown to help slow cellular senescence in Drosophila melanogaster fruit flies.
Beyond such immediately accessible interventions, a new class of drugs dedicated to controlling
cellular senescence named “senolytics” are in early research, and some existing drugs
show promise for possibly being repurposed as senolytics. For example, the widely
used diabetes medication metformin was found to give patients sick with diabetes a
longer lifespan than even their non-diabetic counterparts. Rapamycin is another existing drug
under investigation, with a 2020 study showing it extended lifespan in mice by up to 15%.
Other potential drugs being researched seek to target our DNA. Harvard geneticist David
Sinclair broke major ground and rose to mass media attention after finding boosting the levels
of nicotinamide adenine dinucleotide, or NAD, in aging mice, helped to repair their DNA, restoring
their blood vessels and ability heal organ damage, making them look and act younger. In humans too,
the level of NAD in our cells declines as we age, and NAD is needed by our epigenome to
turn off unneeded genes. Nutraceuticals that increase NAD such as nicotinamide
mononucleotide and nicotinamide riboside have already become popular supplements,
though evidence for these supplements’ benefits in humans remains limited thus-far.
Genetic engineering is another medical strategy that might not be quite as far away as you’d
think. Scientists have already manipulated a gene in mice that extended its life by 50%,
and one in nematode worms that extended its life by 10 times. As of 2020, scientists have
identified 78 possible genes for study that could lead to life extension in humans.
Taking a look further into the future, medical scientists, including those working
at the United States Department of Defense, are studying the use of stem cells and cloning
to grow new body parts – an organic technology that could be used to replace aging organs.
Stem cells also offer a wide variety of other possible uses for rejuvenating our
bodies, being able to heal cellular damage and fix issues with intercellular signaling.
Machine technology offers major opportunities as well. Some futurists have speculated that
developments in nanotechnology may lead to microscopic nanomachines that could operate on
and repair our cells, including transplanting new mitochondria into our cells after their original
ones stop properly functioning. Meanwhile, the “2045 Strategic Social Initiative” is thinking
bigger, hoping to manufacture mechanical organs, and then eventually manufacture full mechanical
bodies that people can transplant their brain into at the end of their body’s life. Although the year
2045 may feel like a wildly ambitious timeline, the initiative also hopes to see a future
in which even the human brain could be transcribed into a digital incarnation.
Whether the mind is uploaded into an artificial body, or virtual world, or
just kept on a server in the cloud, this concept offers the ability for people to keep
loved ones in their life long after their death. Such a future has been widely explored in science
fiction, such as in the Altered Carbon franchise. But whether copying one’s mind into a new entity
actually counts as true immortality or even life extension is a matter of philosophical debate.
As with Star Trek’s famed teleporter question, if a body is destroyed on one side, even if it's
perfectly copied and rebuilt on another, has there been any continuity of consciousness between
the two entities? Is it really the same person? If we achieve immortality, be it by biological
or technological means, the world would be a very different place. While fears of overpopulation
have troubled thinkers since Thomas Malthus, predictions of resource depletion have
consistently failed to pass. But what would happen in a world in which no one dies and our
population continues to climb? What would happen in a world that becomes so crowded there might not
even be enough space let alone food for all of us? Immortality is likely a long way away. But the
progress on the road to get there – extending our lives far beyond the current average lifespan –
is something humanity is very likely to experience much sooner. The first person to live to 125, 150,
or even 200 may have already been born. Perhaps, if you keep yourself healthy, it may even be you.
Is immortality possible? If it is, would you want to live forever?
Join the conversation, and predict the future with us down in the comments.
Beyond Now is a new channel dedicated to helping people connect with humanity and
the universe’s past, and to inspire them to dream about the future. We have big plans to
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